Viloxazine hydrochloride, (±)-2-[(2-ethoxyphenoxy)methyl]morpholine hydrochloride (Structural Formula 1), is a racemic compound with two stereo isomers (R-viloxazine and S-viloxazine). The molecular weight of the hydrochloride salt is 273.8 with a conversion factor for viloxazine base to viloxazine hydrochloride of 1.154.

The pharmacokinetics of viloxazine have been evaluated in six epileptic patients following an intravenous infusion and an oral dose both equivalent to 200 mg of viloxazine base (E. Pisani et al. Psychopharmacology (1986) 90: 295-298). The absolute oral bioavailability was 85% (±14%, standard deviation). The drug was rapidly absorbed following oral administration with a tmax of approximately 2 hours. The observed elimination half-life was 4.3 hours (±1.5 hours, standard deviation).
Viloxazine was previously marketed in several European countries for the treatment of major depressive disorder (MDD). Viloxazine is an inhibitor of the reuptake of norepinephrine, but may also enhance the release of serotonin from neuronal stores. The typical “immediate release” oral dose of viloxazine in MDD, expressed as viloxazine base, was 200 mg-300 mg daily given in 2 to 3 divided doses; in certain cases the daily dose was increased to 600 mg (Vidal® pp 2116-2117 (2007)).
Due to the potentially high therapeutic dose, weakly basic nature of the molecule, and a relatively high in vivo clearance rate in humans, viloxazine presents challenges for developing an extended release formulation. These, and other, challenges have been overcome by the formulations of the instant invention.